It looks to me like laced cord, not pin closures (I think there are two sets of grommets - one in the "flap" and one flat on the front panel of the corset), and it looks like it would be a giant hassle to lace it up over the zipper every time. However, I don't see that the corset separates at the bottom front (the binding below the zipper looks like a continuous piece) so I suspect there's another closure at the back and the front closure is only decorative.
Judging by the amount of wrinkling in the front of the "corset" it's either not boned at all, or only lightly boned with plastic. There could be another zipper at the back since it doesn't look like it was built to cinch her in like a regular corset. Or you could make a proper steel-boned corset with a closed front (and just have the zipper as a decorative element laying on top of the front panel) and have real lacing in the back.
The panel at the top of the sleeve of the jacket looks like it might be suede or microsuede (that material you sometimes see sofas made out of). The pleated part at her elbow looks like it might be made of the same fabric. The texture on the main part of the fabric (the slightly shiny parts on most of the rest of the sleeves - where the zipper is on the right sleeve, for example) could be done the same way Star-Lord's short jacket was, with a pattern printed with glossy paint on top of "regular" fabric.
There is a LOT going on with that jacket. It's gorgeous, but wow that's a ton of details!